CMM Exploration & Production Processes 5 — Questions and Answers
Question 1: What does 'proved developed producing' (PDP) reserves classification mean under SEC definitions?
- Reserves accessible only after new wells are drilled
- Reserves recoverable from existing wells currently on production with current equipment (Correct answer)
- Probable reserves requiring further appraisal drilling
- Reserves discovered but not yet drilled
Correct answer: Reserves recoverable from existing wells currently on production with current equipment
PDP reserves are the highest-confidence category, representing volumes expected from currently producing wells using existing infrastructure.
Question 2: In 3D seismic acquisition, what is the purpose of 'time migration' processing?
- To convert seismic two-way travel time to depth using velocity models
- To reposition seismic reflectors to their true subsurface locations in time domain (Correct answer)
- To filter noise and multiples from raw shot records
- To balance amplitudes across all traces uniformly
Correct answer: To reposition seismic reflectors to their true subsurface locations in time domain
Time migration collapses diffractions and moves dipping reflectors to their correct time-domain positions, improving structural imaging accuracy.
Question 3: Which drive mechanism in a reservoir relies on dissolved gas coming out of solution to provide the energy to push oil to the wellbore?
- Water drive
- Gas-cap drive
- Solution gas drive (dissolved gas drive) (Correct answer)
- Compaction drive
Correct answer: Solution gas drive (dissolved gas drive)
Solution gas drive liberates dissolved gas as reservoir pressure drops below bubble point, and expanding gas bubbles drive oil toward producing wells.
Question 4: What is the significance of the 'dew point' pressure in a gas condensate reservoir?
- Pressure at which water begins to condense from the gas stream
- Pressure below which liquid hydrocarbons condense from the gas phase in the reservoir (Correct answer)
- Temperature at which the gas freezes in the wellbore
- Pressure required to initiate production from a tight formation
Correct answer: Pressure below which liquid hydrocarbons condense from the gas phase in the reservoir
Below dew point pressure, retrograde condensation occurs — liquid hydrocarbons drop out in the reservoir pore space, often becoming unrecoverable.
Question 5: Which technique uses variations in Earth's gravitational field to map subsurface density contrasts, helpful in identifying salt bodies or basement features?
- Magnetic survey
- Gravity survey (Correct answer)
- Electromagnetic survey
- Seismic refraction survey
Correct answer: Gravity survey
Gravity surveys measure gravitational acceleration differences caused by density variations — salt (low density) and basement rocks create characteristic anomalies.
Question 6: In the context of gas lift artificial lift, what is the function of the gas lift mandrel and valve?
- To measure downhole temperature and pressure
- To inject high-pressure gas into the tubing at depth, reducing fluid density and enabling lift (Correct answer)
- To pump fluid mechanically from the reservoir to surface
- To seal production zones from each other
Correct answer: To inject high-pressure gas into the tubing at depth, reducing fluid density and enabling lift
Gas lift valves allow injection of compressed gas at a precise depth, aerating the produced fluid column to reduce hydrostatic pressure and increase production.
Question 7: What regulatory requirement under BOEM governs exploration activities on the US Outer Continental Shelf (OCS)?
- A Resource Conservation and Recovery Act permit
- An Exploration Plan (EP) submitted to and approved by BOEM before drilling (Correct answer)
- An Environmental Impact Statement filed with the EPA only
- A state-level drilling permit issued by the coastal state
Correct answer: An Exploration Plan (EP) submitted to and approved by BOEM before drilling
BOEM requires operators to submit and receive approval of an Exploration Plan detailing drilling, environmental, and safety information before OCS exploration drilling.
CMM Exploration & Production Processes 5
What does 'proved developed producing' (PDP) reserves classification mean under SEC definitions?